1. Field of the Invention
The present invention relates to a method of cooling coated foods, particularly confectionery and baked goods, wherein the goods are moved by a conveyor belt through a cooling duct, and wherein air is used as the cooling agent. Alternatively, the goods are conveyed by a conveyor belt through a cooling duct above base plates forming heat exchangers, wherein a liquid cooling agent flows through the heat exchangers.
2. Description of the Related Art
A method of the above-described type is basically known from DE-A1-43 11 589. In that known method, air is used as the cooling agent. The process is then called convection cooling and/or radiation cooling. It is also known in the art to carry out cooling by means of base plates which are arranged underneath the conveyor belt and through which flows a liquid cooling agent, preferably water. In that case, the process is called contact cooling or radiation cooling.
A combination of the two types of cooling is also known in the art, i.e., cooling takes place on the upper side by a convection cooling with air and on the lower side by a contact cooling by means of base plates. Cooling takes place in a co-current flow method or a counter-current flow method. In the co-current flow method, the conveying direction and the flow direction of the cooling agent are the same. In the counter-current flow method, the flow directions are oppositely directed. The counter-current flow method has the advantage that the difference between the temperature of the cooling agent and the temperature of the products to be cooled is smaller. In the known apparatus, the cooling agent normally flows parallel through the bottom plates.
The method is used in the production of various foods, such as bars, pralines, waffles, sugar products, products having a long service life and fine bakery products, which are totally or partially coated. The coatings are thick or thin layers, particularly of chocolate, caramel, cocoa icing, shortening icing and sugar icing. The coatings are cooled in the cooling duct in order to solidify. The cooling duct may also include other devices for adjusting and controlling the moisture and other parameters.
Cooling and solidification of the coatings is a process which can basically be dimensioned freely in accordance with the rules of thermodynamics. Since structure, gloss and hardness of the coating, for example, of chocolate, must meet certain quality requirements, the selection of the cooling pattern with respect to temperature and speed of the cooling agent is limited in accordance with experiences in the field, so that, for example, the polymorphous cocoa butter in the chocolate crystallizes in a favorable structure. This is called gentle cooling.
When the same products are manufactured and cooled in a production plant over a longer period of time, those skilled in the field are able to adjust the correct production parameters. For example, when operating in the counter-current flow method, the cooling agent enters with a certain temperature and, due to the heating by the products, is discharged with a higher temperature. This temperature is usually kept constant during a production sequence, in order to ensure a uniform quality. Accordingly, the appropriate parameters and, thus, the desired cooling curves can only be adjusted and maintained after a certain production period, particularly when the products have reached the end of the cooling duct. However, after a production start, a production stop and a production interruption, problems occur since the cooling agent temperature at the cooling agent exit, i.e., in the counter-current flow method, is too low at the product entry. At the production start, there are no products in the cooling duct, so that no heat can be transported away. This means that the cooling medium temperature is too low and new entering products are cooled too much. This has a negative influence and usually leads to the production of waste. The same is true in the case of production interruptions.